Hygienic Source-Code Generation Using Functors

TL;DR

This paper introduces a novel approach to source-code generation that uses functors to embed action code, enhancing type safety and error localization in generated code for functional languages.

Contribution

It proposes generating closed functors for source-code tools, enabling type-checked code instantiation and improved error localization, with implementations for Standard ML, OCaml, and Haskell.

Findings

Implemented lexer and parser generators based on functor technique

Enhanced type safety and error localization in generated code

Demonstrated applicability across multiple functional languages

Abstract

Existing source-code-generating tools such as Lex and Yacc suffer from practical inconveniences because they use disembodied code to implement actions. To prevent this problem, such tools could generate closed functors that are then instantiated by the programmer with appropriate action code. This results in all code being type checked in its appropriate context, and it assists the type checker in localizing errors correctly. We have implemented a lexer generator and parser generator based on this technique for Standard ML, OCaml, and Haskell.